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Examples update 04/05/2023 #48

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02-Traffic_management/02-DirectResponse-HTTP-Body/README.md
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https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPDirectResponse
https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPBody
---
gitea: none
include_toc: true
---
# Description
Based on the [previous example](../../01-Getting_Started/01-hello_world_1_service_1_deployment), we configure the [VirtualService](#virtualservice) to return a specific response to the client with the contents of our choice.
This example configures:
Generic Kubernetes resources:
- 1 Service
- 1 Deployments
Istio resources:
- 1 Gateway
- 1 Virtual Service
# Continues from
# Based on
- 01-hello_world_1_service_1_deployment
- [01-hello_world_1_service_1_deployment](../../01-Getting_Started/01-hello_world_1_service_1_deployment)
# Configuration
## Service
Creates a service named `helloworld`.
This service listens for the port `80` expecting `HTTP` traffic and will forward the incoming traffic towards the port `80` from the destination pod.
```yaml
apiVersion: v1
kind: Service
metadata:
name: helloworld
labels:
app: helloworld
service: helloworld
spec:
ports:
- port: 80
name: http
selector:
app: helloworld
```
## Deployment
Deploys a Nginx server that listens for the port `80`.
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: helloworld-nginx
labels:
app: helloworld
spec:
replicas: 1
selector:
matchLabels:
app: helloworld
template:
metadata:
labels:
app: helloworld
spec:
containers:
- name: helloworld
image: nginx
resources:
requests:
cpu: "100m"
imagePullPolicy: IfNotPresent #Always
ports:
- containerPort: 80
```
## Gateway
Deploys an Istio gateway that's listening to the port `80` for `HTTP` traffic.
It doesn't filter for any specific host.
The `selector` field is used to "choose" which Istio Load Balancers will have this gateway assigned to.
The Istio `default` profile creates a Load Balancer in the namespace `istio-system` that has the label `istio: ingressgateway` set, allowing us to target that specific Load Balancer and assign this gateway resource to it.
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: helloworld-gateway
spec:
selector:
istio: ingressgateway # use istio default controller
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "*"
```
## VirtualService
The configuration set, targets the [gateway created](#gateway) as well of not limiting the traffic to any specific host.
We configure 2 rules for HTTP traffic (this includes `HTTPS` and `HTTP2`, this will be my last warning about this).
The first rule configure will match when the requested path is `/helloworld`.
This traffic will be forwarded to the service `helloworld.default.svc.cluster.local` with port `80`.
The second rule, which will manage the rest of the traffic, will return a response with status code `404`, and body content set to `Page Not Found`.
Additionally, for consistency and good practices purposes, we also specified the content type of the page to `text/plain`.
```yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
name: helloworld-vs
spec:
hosts:
- "*"
gateways:
- helloworld-gateway
http:
- name: helloworld
match:
- uri:
exact: /helloworld
route:
- destination:
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite:
uri: "/"
- name: default
directResponse:
status: 404
body:
string: "Page Not Found"
headers:
response:
set:
content-type: "text/plain"
```
# Walkthrough
## Deploy resources
Deploy the resources.
```shell
kubectl apply -f ./
```
```text
deployment.apps/helloworld-nginx created
gateway.networking.istio.io/helloworld-gateway created
service/helloworld created
virtualservice.networking.istio.io/helloworld-vs created
```
## Wait for the pods to be ready
Wait for the Apache and Nginx deployments to be up and ready.
```shell
kubectl get deployment helloworld-nginx -w
```
```text
NAME READY UP-TO-DATE AVAILABLE AGE
helloworld-v1 1/1 1 1 4m1s
helloworld-v2 1/1 1 1 4m1s
```
## Test the service
### Get LB IP
To perform the desired tests, we will need to obtain the IP Istio Load Balancer that we selected in the [Gateway section](#gateway).
On my environment, the IP is the `192.168.1.50`.
```shell
kubectl get svc -l istio=ingressgateway -A
```
```text
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
istio-ingressgateway LoadBalancer 10.97.47.216 192.168.1.50 15021:31316/TCP,80:32012/TCP,443:32486/TCP 39h
```
### helloworld
As expected, we receive the contents from the Nginx contents
```shell
curl 192.168.1.50/helloworld -s | grep "<h1>.*</h1>"
```
```text
<h1>Welcome to nginx!</h1>
```
### other paths
#### /
We receive the contents "Page Not Found".
```shell
curl 192.168.1.50/
```
```text
Page Not Found
```
Checking the headers, we also can see the status code is set to `404`, as well of the content-type we specified on the [VirtualService configuration](#virtualservice).
```shell
curl 192.168.1.50/ -I
```
```text
HTTP/1.1 404 Not Found
content-type: text/plain
content-length: 14
date: Thu, 04 May 2023 01:18:50 GMT
server: istio-envoy
```
#### /found
We can confirm that this behavior applies to other paths (as it is matching the "default" rule we set in [VirtualService configuration]).
```shell
curl 192.168.1.50/found
```
```text
Page Not Found
```
```shell
curl 192.168.1.50/found -I
```
```text
HTTP/1.1 404 Not Found
content-type: text/plain
content-length: 14
date: Thu, 04 May 2023 01:20:40 GMT
server: istio-envoy
```
## Cleanup
Finally, a cleanup from the resources deployed.
```shell
kubectl delete -f ./
```
```text
deployment.apps "helloworld-nginx" deleted
gateway.networking.istio.io "helloworld-gateway" deleted
service "helloworld" deleted
virtualservice.networking.istio.io "helloworld-vs" deleted
```
# Links of interest
- https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPDirectResponse
- https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPBody

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02-Traffic_management/02-DirectResponse-HTTP-Body/Services.yaml → 02-Traffic_management/02-DirectResponse-HTTP-Body/Service.yaml
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@ -10,5 +10,4 @@ spec:
- port: 80
name: http
selector:
app: helloworld
---
app: helloworld

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02-Traffic_management/02-DirectResponse-HTTP-Body/VirtualService.yaml
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---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
@ -15,7 +14,7 @@ spec:
exact: /helloworld
route:
- destination:
host: helloworld
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite: